Signaling system



l0 LEVELS Oct. 22, 1940.

c. E. LOMAX 2,218,848

SIGNALING SYSTEM Filed June 20, 1938 8 Sheets-Sheet l I INVENTOR. Clarence ErnesTLrJmax BY MM A'ITORNEYS.

Oct. 22, 1940. c, {5 LQMAX 2,218,848

SIGNALING SYSTEM Filed June 20, 1938 8 Sheets-Sheet 2 IHHI 2/2 2/3 3/4 2/9216 INVENTOR.

Clarence ErnesTLumax BY [19 M M ATTORNEYfi Oct. 22, 1940. c, E, LQMAX 2,218,848

SIGNALING SYSTEM Fi led June 20, 1958 8 Sheets-Sheet 5 /09 &

O 55 44 H a7 O /05 /04 88 10/ ma 7 2 I02 2 INVENTOR. ElarenceErnesTLnmax BY 6 z I a I,

ATTORNEYS.

Oct. 22, 1940. c. E. LOMAX smmune SYSTEM Fild June 20, 193B 8 Sheets-Sheet 6 ATTORNEYS.

Patented Oct. 22, 1940 UNITED STATES 2,218,848 SIGNAIJNG SYSTEM Clarence Ernest Lomax,

Oak Park, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application June 20, 1938, Serial No. 214,724

44 Claims.

' ratus for use in automatic telephone systems.

In an automatic telephone system, switching apparatus including a large number of switches is necessary for performing the various line switching functions required inestablishing desired connections between the many lines of the system. Switches embodying several types of switching units or mechanisms for performing the above-noted functions are known in the art. One improved form of switching unit which is well adapted for use in the application noted, and which possesses distinct advantages with respect to the features of construction and mode of operation thereof, is disclosed and claimed in the copending application of Hans Sengebusch, Serial No. 214,722, filed June 20, 1938. Briefly described, this switching unit or mechanism is adapted to be associated with a conductor bank formed of uninsulated conductors and comprises a plurality of elementary switches, each of which is selectively operative and includes two line selecting devices which are adapted to be operated together in order to select simultaneously two lines in the conductor bank. Furthermore, the switching unit is so constructed and arranged that it may be incorporated in either a finder or selector switch, as desired. The form of switching unit noted is exceedingly compact and of small size, is economical to manufacture and install, and may be readily incorporated in either of the types of switches noted.

It is an object of the presentinvention to provide a signaling system and, more particularly, an automatic telephone system comprising a plurality of switches embodying switching units of the form noted, and including improved apparatus for controlling the switching units, which consists primarily of standard rotary switches and relays arranged in a simple manner such that a minimum amount of control apparatus is required for a system of a given size.

Another object of the invention is to provide, in a system of the character described, an improved line selecting switch embodying a switching unit of the form noted and including improved apparatus for controlling the operation of the switching unit.

A further object of the invention is to provide, in an automatic telephone system, an impulse responsive line selecting switch embodying a switching unit of the form noted, and including improved apparatus for controlling the automatic operation of the switching unit to select an idle line in a small group of lines.

It is a still further object of the invention to provide, in an automatic telephone system, an impulse responsive line selecting switch and im- 5 proved impulsing apparatus for transmitting a plurality ofseries of impulses to the line selecting switch, thereby to control the operation thereof. In general, the objects as set forth are attained 10 in accordance with the present invention by providing, in a telephone system of the character noted, switching apparatus comprising a. conductor bank formed of uninsulated conductors and a. plurality of finder-connector links, each 15 link including a finder portion or switch and a connector portion or switch, and each switch embodying a switching unit or mechanism of the form noted having access to each line in the conductor bank. The lines in the conductor bank are arranged in a plurality of divisions, each division comprising two groups, each group comprising a plurality of subgroups, at least one subgroup including a small group of lines, and each subgroup including a plurality of lines. The small group of lines of the conductor bank are adapted to be connected by way of line circuits, individual thereto, to P. B. X. lines extending to a private branch exchange; while the remainder of the lines in the conductor bank are adapted to be connected by way of line circuits, individual thereto, to subscriber lines extending to subscriber substations. More specifically, each of the finder switches constitutes an impulse responsive line selecting switch embodying a switching mechanism having access to each of the lines in the conductor bank, and having associated therewith an arrangement including a, circuit for transmitting operating impulses to the switch, a stepping mechanism, means including a motor for operating the stepping mechanism a plurality of steps, the steps being divided into a plurality of active and inactive groups, successive groups of active steps being separated from each other by a group of inactive steps, a circuit for energizing the motor, and means for controlling the energizing circuit to cause the motor to operate the stepping mechanism the active steps at a relatively low speed and to operate the stepping mechanism the inactive steps at a relatively high speed. This arrangement also includes means for transmitting by way of the first-mentioned circuit to the switch a plurality of seriesof operating impulses correspondingto the number of groups of active steps the stepping mechanism is operated, the number of impulses in each series corresponding to the number of steps the stepping mechanism is operated in the corresponding group of active steps, thereby to cause the switching mechanism to select a corresponding line in a corresponding subgroup in the group of lines in the conductor bank.

In accordance with another feature of the invention, each of the connector switches constitutes a line selecting switch comprising a trunk line, a switching mechanism of the form noted having access to each of the lines in the conductor bank, means including an impulse responsive motor for operating the switching mechanism, first and second circuits for energizing the motor, and means for transmitting a plurality of series of impulses by way of the first circuit to the motor to cause the switching mechanism to select one line in the small group of lines in the one subgroup in the one group of lines in the conductor bank. Further, this line selecting switch comprises means including a control relay for testing the idle or busy condition of a selected line in the small group of lines, the control relay being operated in the event the selected one line in the small group of lines is busy, means responsive to the operation of the controlrelay for transmitting a single impulse by way of the second circuit to the motor to cause the switching mechanism to select another line in the small group of lines, means responsive to'the operation of the motor for causing the control relay to restore, the control relay remaining restored in the event the selected other linein the small group of lines is tested idle, and means responsive to the test of an idle condition of the selected other line in the small group of lines for connecting the trunk line thereto. This line selecting switch also includes means responsive to the test of a busy condition of the selected other line in the small group of lines for projecting busy tone current over the trunk line.

In accordance with a further feature of the invention, each line selecting switch comprises a switching mechanism of the form noted, including a plurality of elementary switches individually associated with the divisions of lines in the conductor bank, means including a first operating member for selecting any one of the elementary switches to be operated, thereby tov select the two groups in the associated division of lines, means including a second operating member for causing a selected one ofthe elementaryswitches to select any two corresponding subgroups in the two selected groups of lines, and means including a third operating member for causing the selected elementary switch to select simultaneously any two corresponding lines in the two selected subgroups of lines. Further, each line selecting switch includes afirst impulse responsive means for rendering successive- -ly operative the first, second and third operating members, a second impulse responsive means for selectively operating an operative one of the operating members, a circuit for controlling the impul e responsive means, and control apparatus for the circuit, the control apparatus being so constructed and arranged that during operation thereof a single control impulse is transmitted' by way of the circuit to the first impulse responsive means and a series of control impulses is thereafter transmitted by way of the circuit tothe second impulse responsive means.

In acordan'ce with a still further feature of the invention, each line selecting switch O P i ii switching unit or mechanism of the form noted including a plurality of elementary switches and first, second and third operating members for causing the operation noted of a selected one of the elementary switches, each of the operating members having a normal and a plurality of offnormal positions corresponding, respectively, to idle and operated positions thereof, and means for moving the operating members in a predetermined order from their normal into their oflnormal positions. Further, each line selecting switch includes a reset mechanism for moving the operating members in a different predetermined order from their off-normal back into their normal positions, a motor for operating the reset mechanism, first and second circuits for energizing the motor, means for completing one of said circuits, means responsive to a predetermined operation of the reset mechanism for completing the other of the circuits, means responsive to the movement of at least one of the operating members back into its normal position for interrupting one of the circuits, and means responsive to another predetermined operation of the reset mechanism for interrupting the other of the circuits.

Further features of the invention pertain to the particular arrangement of the circuit elements of the system whereby the above-outlined and additional operating features thereof are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figure 1 is an end elevational view of the front and rear frames of a switching apparatus constructed and arranged in accordance with the present invention; Fig. 2 is a side elevational view of the units carried by the front and rear frames shown in Fig. 1; Figs. 6, 7 and 8, taken together, are a fragmentary plan view of one of the automatic switching units of the switching apparatus; Fig. 9 is a plan view of one of the elementary switches embodied in the automatic switching unit'illustrated, showing the elementary switch in an op-' erated position; Fig. 10 is an end elevational view, partly in section, of the operated elementary switch, taken along the line Illin Fig. 9; Fig. 11 is a fragmentary side elevational view of a re-. set mechanism embodied in the switching unit illustrated, taken in the direction of the arrows il-ll in Fig. 6; Fig. 12 is a sectional view of an element of the operating mechanism embodied in the switching unit'illustrated, taken along the line I2l2 in Fig. 6; Fig. 13 is an enlarged frag- -mentary end elevational view of an escapement' in the switching unit illustrated, taken in the direction of the arrows l4-|4 in Fig. '1; Fig. 15 is a sectional view of the escapement control mechanism, taken along the line l5-l5 in Fig. 14; Fig 16 is a sectional view of an indicator embodied in the switching unitillustrated, taken along the line l6l6 in Fig. 6; and Figs. 17, 18 and 19, taken together, illustrate the details of a complete automatic telephone system having incorporated .therein the switching apparatus shown in Figs. 1 to 16, inclusive.

Referring now more particularly toFigs. 17, 18 and 19 of the drawings, there is illustrated an automatic telephone system comprising an exchange having extending thereto a plurality of subscriber lines and a group of P. B. X. lines, two of the subscriber lines and one. of the group of P. B. X. lines being indicated, respectively, at 304, 610 and 105, and subscriber. controlled switching apparatus for setting up connections between the various lines. In brief, the switching apparatus comprises a conductor bank 24 in or switch connected together by a trunk line.

Thus, the subscriber lines 304 and 610 and the P. B. X. line are adapted to be connected by way of the line circuits 300, 615 and 140, respectively,. to corresponding lines in the conductor bank 24, and the illustrated finder-connector link 50! comprises a finder switch 30! and a connector switch 500 connected together by a trunk line 325. More specifically, the exchange is designed to serve one thousand lines and the conductors in the conductor bank 24 are arranged in five divisions, each division comprising two groups, each group comprising ten levels or subgroups, each subgroup comprising ten lines, and each line comprising a positive, a negative and a control conductor. Distributor and common equipment is associated with each group of lines terminating at the exchange in order to assign the links to the use of the successive calling subscriber lines included in the associated group and to cause the finder switch of an assigned link to find a calling line, the distributor and common equipment associated with a group of lines including the subscriber line 304 being indicated at 302. Preferably, each of the distributors is of the fully directive'type, having access to each link in the exchange and being operative immediately an assigned link seizes a calling line in the associated group to assign another idle link to the use of the next calling line in the associated group.

of the associated subscriber line to the automatic switching equipment embodied in the line terminating exchange.

The end of each P. B. X. line, remote from the exchange housing the switching apparatus illustrated, terminates at the private branch exchange indicated at 100. The private branch exchange 100 includes the usual attendants position which is provided with a transmitter, a receiver, an impulsing device for transmitting switch control impulses by way of any one of the P. B. X. lines to the automatic switching equipment embodied in the line terminating exchange and operator controlled switches for routing connections between the substation lines extending to the private branch exchange.

Each of the line circuits comprises a line relay and a cut-oil relay, the line and cut-oil relays illustrated at R350 and R340, respectively, being embodied in the line circuit 300, the line and cut-oil relays illustrated at R650 and R660,

respectively, being embodied in the line circuit 615, and the line and cut-off relays illustrated at R and R120, respectively, being embodied in the line circuit 140.

The distributor and common equipment associated with each group of lines may be identical with that illustrated at 302. In brief, the dis-. tributor and common equipment 302 comprises two rotary switches 465 and 485, an impulse sender circuit and a plurality of control relays R390, R400 and R4l0.- The rotary switch 465 includes an operating motor M419 and two banks of contacts 461 and 418, having double ended wipers 466 and 411, respectively associated therewith, each wiper being rotatable over the associated contact bank into engagement with the individual contacts therein. The rotary switch 485 includes an operating motor M414 and four banks of contacts 401, 489, 496 and 493 having double ended wipers 486, 488, 490 and 492, respectively associated therewith, each wiper being rotatable over the associated contact bank into engagement with the individual contacts therein. The impulse sender circuit includes an impulse relay R0l5, a control relay R498 and a transfer relay R420.

The finder switch of each finder-connector link in the system may be identical to the finder switch 30L In brief, this finder switch comprises an automatic switching unit or mechanism, two switching relays R860 and R310, and a control relay R380. The automatic switching unit includes five elementary switches, each being provided with two sets of wipers associatedwith the conductor bank 24, the wiper sets of one of the elementary switches of the switching unit being indicated at 45 to 50, inclusive. The automatic switching unit also includes a plurality of operating motors Ml, M2 and M3 and a plurality of contact sets 222, 231, 245, 260*, 210- and 280, the construction and arrangement of the automatic switching unit being described in greater particularity subsequently.

The connector switch of each finder-connector link may be identical to the connector switch 500. an automatic switching unit or mechanism, a line relay R520, a hold relay R530, a battery reversing relay R550, a busy relay R510, a ring In brief, this connector switch comprises cut-off relay R580, a switching-through relay.

. each being provided with two sets of wipers associated with the conductor bank 24, the wiper sets of one of the elementary switches of the switching unit being indicated at 45 to 50", inclusive. Also, the switching unit includes a plurality of operating motors Ml M2 and M3 and a plurality of contact sets 222", 233 231 245 210 and 280 Arrangement of the switching apparatus Referring more particularly to Figs. 1 and 2 of the drawings, it will be observed that the switching apparatus includes front and rear frames 20 and 2|, respectively, the frames being of similar construction and each comprising a plurality of vertical and horizontal members 22 and 23, respectively, secured together in any suitable manner. The frames 22 and 23 are arranged back to back and secured together in spaced relation, the conductor bank 24 being arranged to occupy the space between the backs of the frames. The conductors in the conductor bank 24 extend in a vertical direction and, being uninsulated, serve both as multiple conductors between the automatic switching units and as fixed wiper contacts for the movable wipers of the individual switching units. Also, each conductor is retained in position in its division by a plurality of spaced-apart insulating members 25. The positive, negative and control conductors in each division are segregated into three subdivisions which are arranged in the same manner. The line conductors in each subgroup in each subdivision are arranged in substantially the same vertical plane, each line conductor being spaced from the adjacent line conductor by a fixed distance; and the levels or subgroups in each subdivision are arranged in substantially parallel 'vertical planes, each subgroup being spaced from the adjacent subgroup by a fixed distance. The two groups in each division are so arranged that corresponding lines in each group are engaged simultaneously by two sets of wipers carried by the elementary switch associated with a division and included in the switching unit as is more fully explained subsequently.

Each of the frames 2t and 20 is adapted to support a group of substantially identical automatic switching units in vertical alignment and in such a manner that each switching unit has access to each line in the conductor bank 2 This is accomplished by providing the front frame 20 with a plurality of sets of supporting elements 2'5 and the rear frame 29 with a pillrality of sets of supporting elements 2?. In each frame, each set of supporting elements is spaced in a vertical direction a fixed distance from the adjacent set of supporting elements and comprises two horizontally aligned supporting elements respectively secured to the vertical members 22 disposed at the right-hand and left-hand ends of the frame. switching unit supported by the rear frame 28 from interfering with the switching units supported by the front frame 20, the sets of supporting elements 2i carried by the rear frame 2i are staggered in a vertical direction with respect to the sets of supporting elements 25 carried by the front frame 26. Thus, the switching units of one of the groups have access to sections of the conductor bank 26 disposed between the In order to prevent the switching units of the other group, as illustrated in Fig. 5. Preferably, the group of switching units supported by one of the frames are embodied in the finder switches of the finder-connector links of the system, while the group of switching units supported by the other of the frames are embodied in the connector switches of the finder-connector links of the system, the corresponding finder and connector switches of each link being connected together by a trunk line as previously explained. For example, the group of switching units supported by the front frame 20 may be embodied in finder switches, while the group of switching units supported by the rear frame 2| may be embodied in connector switches.

Construction and operation of the switching units Each of the switching units is of the construction of that described and claimed in the copending application of Hans Sengebusch, previously noted, and includes a base plate 28 which constitutes a shelf adapted to be supported upon one of the sets of supporting elements carried by one of the frames. As best shown in Figs. 3 and 4, the opposite ends of the base plate 28 of one of the switching units supported in the front frame 20 rest upon the upper surfaces of the supporting elements of one of the sets of supporting elements 26. The base plate 23 is provided with an upstanding flange is extending along the front edge thereof which projects over the vertical members 22 disposed at the opposite ends of the front frame Zil. The base plate it is secured in place at each end thereof by an arrangement including a screw til extending through an elongated opening 3! formed in the flange 29 and threaded into an opening in the vertical member 22. Also, an arrangement is provided for locking each end of the base plate 28 securely in place, which comprises a pair of screws 32 threaded in openings formed in the flange 29 and engaging the vertical member 22. The elongated openings 3i formed in the opposite ends of the flange 29 accommodate adjustment of the switching unit in a longitudinal direction with respect to the ends of the front frame 20, and the screws 3!! and 32 accommodate adjustment of the switching unit in a lateral direction with respect to the front and back of the front frame 2ft.

In placing a switching unit in the front frame 20, the base plate 25 of the switching unit is first positioned upon the set of supporting elements 26 disposed at the desired level. The switching unit is then slid laterally into place and adjusted so that the same is in proper alignment with respect to the conductor bank 25. The screws 36 are then inserted through the elongated openings 3! formed in the opposite ends of the flange 29 and tightened into snug engagement with the flange 29. The screws 32 are then tightened into snug engagement with the vertical members 22 disposed at the opposite ends of the front frame 26, thereby securely retaining the switching unit in its adjusted position. The switching unit may be removed from the front frame iii by withdrawing the base plate til after the screws till have been untightened and removed.

Each automatic switching unit is provided with an arrangement, more fully described subsequently, for indicating the idle or particular operated position thereof, which includes a signal visible through an aperture 33 provided in an escutcheon plate 34 secured to the flange 29. Also, an opening 35 is formed in the flange 29 which is adapted to receive a plug in order to facilitate testing of the automatic switching unit.

Referring now to Figs. 6, '7 and 8, there is shown a fragmentary portion of one of the automatic switching units of the switching apparatus, which comprises five elementary switches of identical construction and respectively associated with the five divisions of lines in the conductor bank 24. The illustrated elementary switches 49 and 41, respectively, are associated with the first and fifth divisions of lines in the conductor bank 24, the first division comprising the first and second groups of ten levels or subgroups of lines each, and the fifth division comprising the ninth and tenth groups of ten levels or subgroups of lines each. Each of the elementary switches comprisesa carriage 42 individually provided with an element or slide 43 mounted thereon, a contact controlling member .44 being mounted upon the slide 43. The contact controlling member 44 carries two lines selecting devices in the form of two sets of wipers, the first set of wipers being individual to the odd group in the associated division of lines, and the second set of wipers being individual to the even group in the associated division of lines. More particularly, the first set of wipers comprises the wipers 45, 45 and 41, which are adapted to engage the positive, negative and control conductors, re-

spectively, of the lines in the oddgroup; while the second set of wipers comprises thewipers 48, 49 and 50, which are adapted to engage the positive, negative and control conductors, respectively, of the lines in the even group. Also, a terminal block 5| is mounted on the slide 43 in order to extend electrical connections to-the two sets of wipers.

The carriage 42 of each elementary switch is mounted on a longitudinal guide bar 52 carried by the base plate 28, as best shown in Figs. 9 and 10. The rear edge of the carriage 42 is provided with a downwardly extending flange 53 which slidably engages a cooperating guide plate 54 individual thereto. The guide plate 54 is secured to an upstanding flange 55 provided on the rear edge of'the base plate 28. Each of the carriages 42 has a normal position and is movable along a longitudinal path into ten off-normal positions respectively corresponding to the ten levels or subgroups in the odd and even groups in the associated division of lines in the conductor bank 24. The movement of the slide 43 on the carriage 42 is guided at the front edge of the slide by a screw 56 which rides in a slot, not shown, provided in the carriage '42, and at the rear edge of the slide by two downwardly extending lugs 51 formed thereon which cooperate with two guide arms 58 provided on the carriage 42.

Y Each of the slides 43 has a normal position and is movable along a lateral path into ten off-normal positions respectively corresponding to the ten lines in each level or subgroup in the. odd

' and even groups in the associated division.

independently movable. Each of the operating bars has a normal position and is movable toward the left into ten off-normal positions. The movements of the bars toward the left when they reach their tenth oil-normal positions are arrested by a stop 62 secured to'the base plate 28 by screws 62.

The hundred bar 59 carries five lugs thereon respectively associated with the five elementary switches, the illustrated lugs 54 and 65 being respectively associated with the elementary switches 49 and 4|. an off-set finger which is adapted to engage a latch mounted on the carriage of the associated elementary switch. The lugs 64 and 65 are provided with oii-set fingers 64 and 65 respectively, which are adapted respectively to engage latches 66 and 61 pivotally mounted on the carriages 42 of the elementary switches 40 and 4!, respectively. The latch 66 is pivotally mounted at 68 upon the carriage 42 of the elementary switch 40 and is biased by aspring, not shown, away from an associated slot 59 formed in a bar 19 rigidly secured by a strap 1|.to the ten bar 69. When the finger 64 on the lug 64 engages the latch 66, the latter is moved-into the associated slot 59 inorder to lock the carriage 42 of ,the elementary switch 49 to the bar 19 for movement in a longitudinal direction with the ten bar 69, thereby selecting the elementary switch 49 to be operated or rendering the elementary switch 49 operable to select a line from the first and second groups in the first division of lines in the conductor bank 24. The latch 61 is con-- structed in a, similar manner, being adapted to be moved into an associated slot "formed in the bar 19, when the latch 6'! is engaged by the finger 65 on the lug 65. The lugs 64, etc., are successively spaced along the hundred bar 59 and arranged in such a manner that the fingers on the lugs successively engage the latches mounted on the carriages of the elementary switches as the hundred bar .59 is moved from its normal position, the fingers being arranged to engage the latch associated therewith when the hundred bar 59 occupies two adjacent off-normal positions. Thus, the finger. 54 engages the latch 56 when the hundred bar 59 is moved from its normal position into its first oil-normal position, thereby locking the carriage 42 or" the elementary switch 40 to the bar 10; and the finger 54 remains in engagement with the latch 56 when the hundred bar 59 is moved into its second onnormal position. The latch 65 rides off of they end of the finger 54 on the lug 64 carried by thehundred bar 59 when the hundred bar 59 is moved into its third off-normal position, thereby unlocking the carriage 42 of the elementary switch 49 from the bar 10. Thus, the carriage of the first elementary switch 49 is locked to the bar 19 when thehundred bar occupies its first and second cit-normal position; the carriage of the second'elementary switch is locked'to the bar I9 when the,hundred bar 59 occupies its third and fourth cit-normal position; etc. The arrangement oi! the lugs 54, etc., on the hundred bar 59 allows only one of the elementary switches to be rendered operable or'to be selected forv operation at any time; and any one 01' the elementary switches may be selected to be operated by moving the hundred barto a corresponding off-normal position.

After the hundred bar 59 has been moved from its normal position into a predetermined ofl-normal position to cause a corresponding ele- Each of the lugs is provided with mentary switch to be selected and the carriage thereof to be locked to the bar I0,the' ten bar 60 is moved from its normal position into a predetermined off-normal position, causing the carriage 42 of the selected elementary switch to be moved longitudinally toward the left from its normal position into a corresponding off-normal position, thereby to select corresponding levels or subgroups from the odd and even groups in the associated division of'lines in the conductorv bank 24. The carriage 42 of the selected elementary switch is moved with the ten bar 60 due to the engagement between the latch mounted on the carriage 42 o! the selected elementary switch and the associated slot formed in the bar 10 rigidly secured to the ten bar 60. The latch is retained in position in the associated slot during the movement of the ten bar 60 by a member individual to the selected elementary switch and having a guide edge associated with the latch. The illustrated members 12' and I3 are individual to the elementary switches 40 and 4|, respectively, and have the guide edges I4 and I5 respectively associated with the latches 66 and 61, respectively. The members I2 and I3 are secured to a bar 16 by two sets of screws 11 and I8, respectively, the bar I6 being secured to the brackets 82. This arrangement positively insures that the carriage 42 of the selected elementary switch is locked to the bar I during the entire longitudinal movement of the bar I0 with the ten bar 60.

After the ten bar 60 has been moved from its normal position into a predetermined off-normal position, causing the carriage 42 of the selected elementary switch to be moved from its normal position into a corresponding off-normal position, thereby to select corresponding levels or subgroups from the odd and even groups in the associated division of lines, the unit bar BI is moved from its normal position into a predetermined off-normal position. This movement of the unit bar GI causes the slide 43 mounted on the carriage 42 of the selected elementary switch to be moved laterally from its normal position into a corresponding ofi -normal position, thereby to select corresponding lines from the previously selected levels or subgroups of lines. This movement of the slide 43 in response to the movement of the unit bar BI is effected by an arrange-.

ment including an under-slide I9 and a bell crank 90 individual to the selected elementary switch, as is best shown in the operated elementary switch in Figs. 9 and 10. The under-slide i9 is mounted for movement in a lateral direction upon two substantially parallel laterally extending guide members secured to the base plate 28. One of these guide members comprises two aligned rods BI and 8|", while the other guide member comprises an angle bar 82. The underslide it is provided with two outwardly extending arms 83 and 84 embracing the guide rods 8| and 8!! and an outwardly extending arm 85 engaging the guide bar 82 in order to guide the lateral movement of the under-slide I9. Also, an upstanding flange 8B is provided on the rear edge of the under-slide l9 which slidably engages a downwardly projecting button 81 carried by the slide 33 of the selected elementary switch, the button 8] having a slot therein which straddles the upper edge of the flange 86. This arrangement allows the carriage t2 and the slide d3 of the selected elementary switch to be moved longitudinally with respect to the under-slide I9 without any interference therewith.

of the slide 43 thereof.

The bell crank 90 is pivotally mounted at 99 upon a bracket 89 secured by screws 90 to the base plate 28. The bell crank 90 is provided with three outwardly extending arms 9|, 92 and 93 and is biased in a clockwise direction by a coil spring 94 extending between the outer end of the arm 9| and a fixture 95 carried by the base plate 28. The outer end of the arm 93 carries a roller 96 which engages an elongated slot 91 provided in the under-slide 19, the engagement between the roller 96 and the slot 91 constituting a driving engagement between the bell crank 80 and the under-slide 19. The outer end of the arm 92 engages an upstanding flange 98 provided on a fixture 99 secured to the unit bar 8| by a screw I00.

A locking arrangement is provided in each elementary switch in order to control the movement The locking arrangement individual to the elementary switch 4| comprises a locking plate IOI secured to a bar I02 by screws I03, the bar I02 being secured to the brackets 62. The locking plate IOI is provided with a downwardly extending flange I04 having ten notches I05 therein which correspond to the ten off-normal positions of the carriage 42 and cooperate with an upstanding flange I06 provided on one side of the slide 43 adjacent the rear end thereof. More specifically, the rear end of the flange I06 engages the flange I04, when the carriage 42 of the elementary switch 4| occupies its normal position, thereby to lock the slide 43 of the elementary switch H in its normal position against movement in a lateraldirection. When the elementary switch H is selected to be operated and the carriage 42 thereof is moved longitudinally from its normal position into a predetermiried ofi-normal position, the rear end of the flange I06 is moved into alignment with a corresponding notch I05 in the flange I04, thereby to unlock the slide 43 formovement in a lateral direction, the slide 43 being restrained against movement in a lateral direction by the engagement between the flange 98 on the fixture 99 secured'to the unit bar GI and the outer end of the arm 92 on the bell crank 80, at this time.

After the carriage 42 of the selected elementary switch 4! has been moved longitudinally into a predetermined ofl-normal position by the ten bar 60, the unit bar 6| is moved longitudinally toward the left into a predetermined oif-normal position. As the unit bar GI is moved longitudinally, the flange 98 on the fixture 99 is moved away from the outer end of the arm 92 on the bell crank 80, causing the spring 94 to rotate the bell crank 80 in a clockwise direction about the pivot 89. It is noted that the flange 98 on the fixture is sufliciently wide to prevent the outer end of the arm 92 on the bell crank 80 from disengaging the flange 98 as the bell crank 80 is rotated in a clockwise direction about the pivot 88. Rotation 01 the bell crank 90 in a clockwise direction causes the under-slide 19 to bemoved laterally toward the rear of the switching unit through the driving engagement between the roller 96 carried by the arm 93 on the bell crank 80 and the slot 91 in the under-slide I9. This movement of the under-slide 179 is transmitted to the slide 43 through the driving engagement between the flange 85 on the under-slide I9 and the button 01 carried by the slide 43. The lateral movement of the slide as is the same as that of the underslide I9, which latter movement is proportional to the rotational movement of the bell crank 80,

. moved longitudinally, due to the fact that the rear or right-hand end of the flange I06 on the slide 43 of only the selected elementary switch 41 will be aligned with a notch I05 in the fiangel04 on the locking plate IOI, as shown in Fig. 10. The rear ends of the flanges I06 on the slides 43 of the remainder of the elementary switches engage the flange I04 on the locking plates IOI associated therewith, thereby locking the slide 43 of the remainder of the elementary switches against lateral movement. When the slide 43 of the selected elementary switch M is moved into its first oif-normal position the flange I08 thereon enters the notch I05 in the flange I04 on the lockingplate IOI. This engagement between the flange I06 and the notch I05 in the flange I04 locks the carriage 42 of the selected elementa y switch 4| against further movement in a longitudinal direction.

The rear edge of the carriage 42 of each elementary switch carries three insulating buttons I01, I08 and I09, respectively, arranged between the positive wipers 45 and 48, the negative wipers 4B and 49, and the controlwipers 41 and, 50, carried by the contact controlling member 44 mounted on the slide 43 thereof. These buttons cooperate with inwardly bent portions of the associated Wipers in order to prevent vibration of and engagement between the respective positive, negative and control wipers of the first and sec ond contact sets, when the slide 43- of the elementary switch occupies its normal position. When the slide 43 of the selected elementary switch is moved from its normal position into its first ofi-normal position, the wipers of the first and second contact sets are moved respectively into engagement with the first lines of the adjacent levels or subgroups in the odd and even groups in the associated division of lines, and the inwardly bent portions of the wipers are moved out of engagement with the associated insulating buttons I01, I08 and I09. Also. each of the guide rods 8| is provided with a stop H0 in order to arrest the movement of the under-slide I9, when the unit bar 6| is restored to its normal position. This stop IIO limits the lateral movement of the slide 43 of the elementary switch by engaging the arm 84 on the under-slide I9, and insures that the slide 43 will be arrested in its normal position.

In order to restore the operated elementary switch 4| to its idle position, the unit bar 5| is first moved toward the right back into its normal position. This movement of the unit bar 6| .causes the bell crank 80 to be rotated in a counterclockwisedirection about the pivot 88 against the bias of the spring 94, due to the driving engagement between the flange 98on the fixture 99 secured to the unit bar BI and the outer end o'the' arm 92 on the bell crank 80. This counterclockswitching unit through the driving engagement between the roller 96 carried by the outer end oi under-slide 19 is transmitted to the slide 43 through the driving engagement between the flange 86 on the under-slide 19 and the button 81 carried by the slide 43, causing the slide 43 to be moved laterally toward the front or left-hand end of the switching unit, as shown in Fig. 10, back into its normal position. When the slide 43 is moved back into its normal position, the flange I06 thereon disengages the notch I05 in the flange I04 on the locking plate IOI, thereby to unlock the carriage 42 of the elementary switch 4| for movement in alongitudinal direction back into its normal position. The ten bar 60 is then moved toward the right back into its normal position, causing the carriage 42 to be moved toward the right back into its normal position through the driving engagement between the latch mounted on the carriage 42 and the associated 20 slot in the bar I0 rigidly secured to the ten bar 60. When the carriage 42 is moved back into its normal position, the rear end of the flange I06 on the slide 43 reengages the flange I04 on the looking plate IOI, thereby to lock the slide 43 of the elementary switch against movement toward the rear of the switching unit. Finally, the hundred bar 59 is moved toward the right back into its normal position, causing the finger 65 on the lug 65 carried by the hundred bar 59 and associated 30 with the latch 01 mounted on the carriage 42 of the selected elementary switch 4| to disengage the latch, thereby allowing the spring biased latch to move out of the associated slot 12 in the bar switch from the bar 10 and to restore the same to its idle position. Thus, the switching unit is completely restored to its idle position at. this time and may be reoperated as described above in order to select corresponding lines from sub- :40

groups in the odd and even groups in any division of lines in the conductor bank 24.

In order to control the operating bars 59, 60 and 6| in the switching unit in the manner described above, an operating mechanism is pro- 45 vided which includes an escapement mechanism I II and a reset mechanism I I2, shown in Figs. 6, 7 andll to 16-, inclusive. The escapement mech-' anism I II includes three identical gears H3, H4

and H5 rotatably mounted on a fixed shaft H0, .5

ciated, respectively, in driving engagement with three racks II9, I20 and I2I, which are respectively secured to the operating bars 59, 80 and 0 I, the rack I I9being secured to the hundred bar 59 by a rivet illustrated at I 22. The racks II9, I20

and I2I are biased toward the left by three operating levers I23, I24 and I25 respectively secured thereto by pin and slot connections I26, I21 and I28, respectively. The levers I23, I24 and I25 are of identical construction, each being pivoted at one end to a pin I29 secured to the base plate 28 and being biased by a spring I30 individual thereto in a clockwise direction about the pivot pin I29. One end of each of the springs I30 is fixed to a pin I3I secured to the base plate 28 and the other end thereof is fixed to a corresponding one of the levers I23, I24 and I25. The gears I I3, I I4 and H5 arerestrained against movement in a counterclockwise direction by the associated driving racks II9, I20 and I2I, respectively, by-

toothed escapement wheels I32, I33 and I34 re- 15 10, in order to unlock the selected elementary spectively secured thereto. The escapement wheels'I32, I33 and I34 are provided with escapement members I35, I36 and I31, respectively, pivotally mounted on a pin I38 secured between the bracket H1 and the base plate 28. The escapement members I35, I36 and I31 are of identical construction, and each comprises an escapement pawl and an outwardly extending operating arm. Each of the escapement members is biased in a clockwise direction about the pivot pin I38 by a spring individual thereto, in order to bring the escapement pawl thereon into engagement with the associated escapement wheel. More specifically, the escapement member I35 comprises an escapement pawl I39 and an-outwardly extending operating arm I40 and-is biased by a spring MI in a clockwise direction about the pivot pin I38, in order to bring the escapement pawl I39 into engagement with the associated escapement wheel I32. One end of each of the springs individual to the escapement members I35, I36 and I31 is fixed to a pin I42 secured to the base plate 28, and the other end thereof is fixed to a corresponding one of the escapement members.

The escapement mechanism I II also includes an operating motor MI of the electromagnetic type, comprising a winding I43 and a magnetic structure including a core I44, a frame I45and an armature I46. The armature I46 is pivotally mounted to the frame I45 by a pin I41 and is biased in a clockwise direction about the pivot pin I41 away from the core I44 into engagement with a stop I48 by a coil spring I49, one end of the spring I49 being fixed to the armature I46 and the other end thereof being fixed to a pin I50 secured to the base plate 28. An arrangement including a plate II secured to the armature I46 by a screw I62 and provided with a striking flange I53 extending toward the operating arms of the escapement members I35, I36 and I31 is provided for operating the escapement members, thereby to rotate the escapement members in a counterclockwise direction about the pivot pin I38 in order to move the escapement pawl thereon out,

of engagement with the associated escapement wheels I32, I33 and I34. When one of the escapement members is thus rotated to move the escapement pawl thereon out of engagement with the associated escapement wheel, the associated escapement wheel allows the gear secured thereto to be driven in a counterclockwise direction by the associated rack in driving engagement therewith, thereby to move the associated operating bar longitudinally toward the left.

An arrangement including a mechanism I54 is provided in order to control the escapement mechanism III. This escapement control mechanism I53 comprises a ratchet wheel I55 rotatively mounted upon a fixed pin I56 secured to the base plate 29, and three substantially disc-shaped cam members I51, I58 and I59 rigidly secured to the ratchet wheel I 55, as best shown in Figs. '7, 14 and 15. The periphery of each of the cam members is provided with a plurality of projections which are spaced apart by intervening depressions. More specifically, the cam member I51 is provided with four projections I51? which are spaced apart by intervening depressions I51 In a similar manner, the cam members I56 and I59, respectively, are provided with four projections I58 and I59, which are respectively spaced apart by intervening depressions I58 and I59". Three bell cranks I60, I6! and I62 are respectively associated with the cam members I51, I58 and I59, these bell cranks being pivotally mounted on a pin I63 extending between the bracket H1 and the base plate 28. Each of the bell cranks is provided with two outwardly extending arms, the extreme outer end of one of the arms having a finger adapted to ride upon the periphery of the associated cam member. More specifically, the bell crank I60 is provided with two outwardly extending arms I60 and I60, the extreme outer end of the arm' I60 having a finger I60 adapted to ride upon the periphery of the associated cam member I51. In a similar manner, the bell cranks I6I and I62 are respectively provided with two outwardly extending arms I6I I6I and I62 I62 the extreme outer ends of the arms I6 I and I62 being respectively provided with fingers I6I and I 62 adapted respectively to ride upon the peripheries of the cam members I58 and I59. Three tappets I64, I65 and I66 are respectively pivotally secured by rivets I61, I69 and I69, respectively. to the arms I60, I6I and I62 respectively, of the bell cranks I60, I6I and I62 respectively. Each of the tappets is provided with a head to which one end of a coil spring individual thereto is fixed, the other end of the spring being fixed to a pin I secured to the base plate 28. More specifically, the tappet I64 is provided with a head I64 to which one end of the coil spring I1I individual thereto is fixed, the other end of the spring I1I being fixed to the pin I10. In a similar manner, the tappets I65 and I66 are provided, respectively, with heads I65 and I66 to which the coil springs I12 and I 13 individual to the tappets I65 and I66, respectively, are secured, the other ends of the springs I12 and I13 being secured to the pin I10. The tappets I64, I65 and I66 are arranged between the operating arms of the escapement members I35, I36 and I31 and the striking flange I53 provided on the plate I5I secured to the armature I46. Normally, the springs I'II, I12 and I13 bias the heads I64 I65 and i66 respectively, of the tappets I64, I65 and I66, respectively, toward the front of the switching unit out of positions of engagement with the striking flange I53. The biases of the springs I1I, I12 and I13 cause the bell cranks I60, I6I and I62, respectively, to be rotated in a clockwise direction about the pivot pin I63, thereby bringing the fingers I60, IGI", and I 62, respectively, into engagement with the peripheries of the cam members I51, I58 and I59, respectively.

The escapement control mechanism I54 is so constructed and arranged that when the finger on the extreme outer end of one of the arms of the bell crank engages one of the depressions in the periphery of the associated cam member, the bell crank is rotated in a clockwise direction about the pivot pin I63 by the coil spring extending between the pin I10 and the head of the tappet pivotally mounted on the other arm of the bell crank, thereby causing the head of the tappet to be moved out of striking position with respect to the striking fiange I53 on the plate I5I carried by the armature I 46. On the other hand, when the finger on the extreme outer end of one of the arms of a bell crank engages one of the projections on the periphery of the associated cam member, the bell crank is rotated in a counterclockwise direction about the pivot pin I63 against-the bias of the coil spring extending between the pin I10 and the head of the tappet pivotally mounted on the other arm of the bell crank, thereby causing the head of the tappet to be moved into striking position with respect to the striking flange I53 on the plate I5I secured to the armature I46. The movements of the tappets into their striking positions are tion about the pivot pin I63 by the coil spring I1I extending between the pin I10 and the head I64 of the tappet I64 pivotally mounted by the rivet I61 on the arm I60 oi the bell crank I60, thereby causing the head I64 01 the tappet I64 to be .moved out of striking position with respect to the striking flange I53 on the plate I5I carried by the armature I46. On the other hand, when the finger I60 on the extreme outer end of the arm I60 of the bell crank I60 engages one of the projections I51 on the periphery of the associated cam member I51, the bell crank I60 is rotated in a counterclockwise direction about the pivot pin I63 against the bias of the coil spring I" extending between the pin I and the head I64 of the tappet I64 pivotally mounted by the rivet I61 on. the arm I60 of the bell crank I60, thereby causing the head I64 of the tappet I64 to be moved into striking position with respect to the striking flange I53 on the plate I5I carried by the armature I46. The construction and arrangement of each of the bellcranks I6I and I62 associated with the cam members I58 and I59, respectively, is the same as that of the bell crank I60 described above.

When the head of any one of the tappets is moved into striking position with respect to the striking flange I53 on the plate I5I carried by the armature I46, the associated escapement member pivotally mounted on the pin I38 is conditioned to be operated to allow the associated escapement wheel to be rotated in a counterclockwise'direction by the associated rack in driving relation with the gear secured thereto. More specifically, when the head I64 of the tappet I64 is moved into striking position with respect to the striking flange I53, the associated escapement member I pivotally mounted on the pin I38 is conditioned to be operated to allow the associated escapement wheel I32 to be rotated ina counterclockwise direction by the associated rack H9 indriving relation with the gear I I3 secured thereto.

At this time, when the operation motor MI is energized, the armature I46 thereof is moved in a counterclockwise direction about the pivot pin I41 against the bias of the coil spring I49, causing the striking flange I53 on the plate I5I car-- ried by the armature I46 to engage the head I64 of the tappet I64. The head I64 of the tappet I64 is then moved into engagement with thearm I on the escapement member I35, thereby to cause the escapement member I35 to be rotated in a counterclockwise direction about the pivot pin I 38 against the bias of the coil spring I4I. When the escapement member I35 is rotated in a counterclockwise direction, the escapement pawl I39 is moved out of engagement with the escapement wheel I32, thereby allowing the rack H9 in driving engagement with the gear H3 secured to the escapement wheel I32 to move the escapement wheel I32 one step in a counterclockwise direction, further movement of the escapement wheel in a counterclockwise direction being arrested by the inwardly curved finger I40 provided on the-operating arm I40. The finger I40 on the operating arm I40 serves as a detent to prevent further counterclockwise rotation of the escapement wheel I32. The rotation of the wise direction allows the rack IIO to be moved longitudinally one step toward the left by the lever I23 mounted on the pivot pin I29 and pivotally secured by the pin and slot connection I26 to the rack II9, this movement of the rack I I9 being produced byrotation of the lever I23 in a clockwise direction about the pivot pin I29 under the influence of the coil spring I30. This movement of the rack H9 is transmitted to the hundred bar 59 connected to the rack II9, causing the hundred bar to be moved longitudinally one step from its normal position into itsfirst off-normal position, thereby to cause the first elementary switch 40 to be selected to be operated as previously explained. When the'operating motor MI is deenergized, the armature I46 thereof is rotated in a clockwise direction about the pivot pin I41 by the coil spring I49, causing the head I64 of the tappet I64to disengage the operating arm I40 of the escapement member I35, thereby allowing the escapement member I35 .to be rotated in a clockwise direction about the pivot pin I38 by the coil spring I. When the escapement member I35 is rotated in a clockwise direction, the detent I40 disengages the escapement wheel I32 shortly after the escapement pawl as previously explained.

The striking flange I53 on the plate I5I carried by the armature I46 is sufficiently long to engage the head of any one of the tappets I64, I65 and I66, which occupies a striking position.

. Thus, it will be apparent that the hundred bar 59, the ten bar 60 and the unit bar 6| may be selectively operated by selectively moving the heads of the tappets I 64, I 65 and I66 into striking positions, the number of steps which any one of the operating bars is moved longitudinally toward the left being dependent upon the number of times the operating motor MI is repeatedly energized while the head of the corresponding tappet occupies a striking position. From the foregoing it is apparent that the operating bars 59, 60 and 6I may be selectivelymoved fromtheir normal positions into any one of their oifnormal positions by selectively controlling the movements of the tappets I64, I65 and I66, and by selectively controlling the number of times the operating motor MI is repeatedly energized when the tappets occupy striking positions.

The escapement control mechanism I54 arso includes an operating motor M2 of the electromagnetic type, comprising a winding I 14 and a magnetic structure including a core I15, a frame I16 and an armature I11. The armature I11 is I32, the escapement pawl cured to the base plate 28, while the stop I 8| is carried by a bracket I88 secured by screws I84 to the base plate 28. A pawl I85 is pivotally mounted by a pin I88 to the extreme outer end of 5 the arm I19 and is biased in a clockwise direction about the pivot pin I88 by a coil spring I81 extending between the pawl I85 and the arm I18. The pawl I85 is biased by the spring I81 into engagement with the associated ratchet wheel I55 and the movement thereof is guided by a guide bracket I88 secured by a screw I89 to the base plate 28. Also, a detent I90 pivotally mounted on a pin I8I secured to the base plate 28 is provided in order to retain the ratchet wheel 15 I55 in any one of its operated positions, the detent I90 being biased by a spring I9I' into engagement with a stop I92 secured to the base plate 28. When the winding I14'of the operating motor M2 is energized, the armature I11 is 30 moved in a counterclockwise direction about the pivot pin I18, causing the pawl I85 carried by the arm I19 to be moved away from the associated ratchet wheel I55 against the bias of the spring I80. When the winding I14 of the operating 25 motor M2 is then deenergized, the armature I11 is rotated in a clockwise direction about the pivot pin I18 ,by the spring I80, causing the arm I18 to be moved into engagement with the stop I I8I, thereby to cause the pawl I85 to engage the 30 ratchet wheel I55. The engagement of the pawl I85 and the associated ratchet wheel I55 causes the ratchet wheel I55 to be rotated one step in a clockwise direction, the ratchet wheel being retained in this operating position by the detent 35 I90. Each time the winding I14 of the operating motor M2 is energized and then deenergized, the ratchet wheel I55 is rotated one step in a clockwise direction as explained above.

The four projections on each of the cam mem- 4a bers I51, I58, I59 are equally spaced apart a distance equal to five steps of the ratchet wheel I55 to which each of the cam members is secured, and the cam members are so arranged with respect to each other that the projections 455 on the peripheries thereof are disposed in staggered relation in a manner more particularly described below. When the switching unit occupies an idle position, the ratchet wheel occupies a normal position wherein the fingers I89 59 I8I and I82 engage depressions I51 I58 and I59 in the peripheries of the cam members I51, I58 and I59, respectively, thereby causing the heads of the tappets I89, I85 and I88 to occupy their non-striking positions, as previously ex- 55 plained. When the. switching unit is operated, the ratchet wheel I55 is first rotated one step in a clockwise direction into a first oil-normal position wherein the finger I80 engages a projection I51 on the periphery of the cam member I51 and the fingers I8I and I82 respectively engage depressions I58 and I59 formed in the peripheries of the cam members I58 and I59, respectively, thereby causing the head of the tappet I56 to be moved into its striking position and the heads of the tappets I85 and I88 tobe retained in their non-striking positions. The ratchet wheel I55 is then rotated into a second off-normal position wherein the finger I8I engages a projection I58 on the periphery of the cam member I58 and the fingers IIIIZI and I82 respectively engage depressions I51 and I59 formed in the peripheries of the cam members I51 and I59, respectively, thereby causing the head of the tappet I65 to be moved into its [5 striking position and the heads of the tappets I84 and I88 to occupy theirnon-striklng positions. The ratchet wheel I55 is then rotated into a third oil-normal position wherein the finger I82 engages a projection I58 on the periphery of the cam member I58 and the fingers I80 and 5 I8I respectively engage depressions I51 and I58 formed in the peripheries of the cam members I51 and I58, respectively, thereby causing the head of the tappet I88 to be moved into its striking position and the, heads of the tappets I84 and I85 to occupy their non-striking positions. The ratchet wheel I55 is then rotated into a fourth oil-normal position wherein the fingers I80, I8I- and I82 engage depressions I51", I58 and I58 in the peripheries of the cam members I51, I58 and I58, respectively, thereby causing the heads of the tappets I54, I85 and I88 to 00- ,cupy their non-striking positions. When the operated switching unit is restored to its idle position, the ratchet wheel I55 is rotated into a fifth oft-normal position wherein the fingers I80, I8I and I-82 engage depressions I51", I58 and I59 in the peripheries of the cam members I51, I58 and I59, respectively, as explained in connection with the positions of the fingers when the ratchet wheel I55 occupies its normal position, the fifth off-normal position of the ratchet wheel I55 constituting a normal position thereof for the next cycle of operation of the switching unit.

The reset mechanism II2 comprises an operating motor M3 including a magnetic structure having two core legs I93 and I94 displaced substantially 90 with respect to each other and provided with energizing windings I95 and I98, respectively. The operating motor M3 also includes a frame I91 secured by a number of screws I98 to the base plate 28, and a bracket I99 secured by a number of screws 200 to the frame I91. A rotor 20I is disposed between the core legs I 83 and I94 and is rotatably mounted In between the frame I91 and the bracket I99. The rotor 2IlI includes two diametrically disposed pole pieces 202, each provided with an elongated leading pole tip 202. A commutator arrangement is provided for the operating motor M3, which includes a substantially disc-shaped insulating cam 203 mounted on the rotor- 20d and two contact sets 204 and 205, in order to control the energization of the windings I95 and I98. The contact set 204 includes two cooperating resilient contact springs 206 and 201 biased into engagement and movable into disengagement, and the contact set 205 includes two cooperating resilient contact springs 208 and 209 biased into engagement and movable into disengagement. The contact springs 201 and 209 of the contact sets 200 and 205, respectively, are extended into engagement with the periphery of the insulating cam 203, these contact springs being adapted to ride upon the periphery of the insulating cam. The periphery of the cam 203 is provided with two diametrically disposed projections 2033 having gradually inclined surfaces therebetween, the arrangement being such that the contact springs of the contact sets 204 and 205 are alternately engaged. The windings I95 and I98 are energized in parallel circuit relation from a suitable source of direct current supply. The contact set 20 3 is included in series circuit relation with the winding I98, and the contact set 205 is included in series circuit relation with the winding I95.

This commutator arrangement causes the contact springs of the contact set 204 to be disengaged and the contact springs of the contact set 205 to be engaged, when the leading edge'of v the pole-tip 282 on one 01' the pole pieces 282 occupies a position adjacent the leading tip of the core leg J93, thereby to cause the winding I95 to be energized and the winding I98 to be de'energized. Also, this commutator arrangement causes the contact springs of the contact set 204 to be engaged and the contact springs of the contact set 285 to be disengaged, when the leading edge of the pole tip 202 on one of the pole pieces 202 occupies a position adjacent the leading tip or the core leg I94, thereby to cause the winding I96 to be energized and the winding I95 to be deenergized. The alternate energization of the windings I95 and I96 causes the rotor 2III to be rotated in a clockwise direction in a well known manner.

The rotor 29I of the operating motor M3 is arranged in driving relation with a reset cam member 2I0'rigid1y secured to a pin ZI I rotatably supported by the base plate 28. The reset cam member 2I8 is driven by the rotor I through a gear train including a pinion 2 I2 rigidly secured to the shaft of the rotor 2M. The pinion 2I2 is arranged in driving relation with a gear 2I3 rotatably supported on a pin 2I4 and secured to the base plate 28. The gear 2 I3 is rigidly secured to a pinion 2 I5 arranged in driving relation with a gear 2I6 rigidly secured to a pin 2II rotatably supported by the base plate 28. Also, a pinion 2 I8 is rigidly secured to the pin 2I'I and arranged in driving engagement with a gear 2I9 rigidly secured to the pin '2! I. The cam member 2I 0 carries a roller 220 and the gear 2 I9 carries a roller 22I the roller 220 being associated with two reset fingers I23 and I24 provided on the operating levers I23 and I24, respectively, and the roller 22I being associated with a reset finger I25 provided on the operatinglever I25. The roller 220 is adapted to engage the ends of the fingers I23 and I 24 when the cam'2II is rotated in a counterclockwise direction by the operating motor M3, in order to cause the lever I25 to be rotated in a counterclockwise direction about the pivot pin I29, thereby to cause the unit bar iii to be moved longitudinally toward the right from its predetermined off-normal position back into its normal position. The rollers 220 and 22I are disposed angularly' with respect to each other in such a manner that the roller 22I is brought into engagement with the finger I25 before the roller 228 is brought into engagement with the fingers I23 and I24 thereby causing the unit bar 6I to be moved back into its normal position prior to the movement of the ten bar 60 and the hundred bar 59 back into their normal positions.

From the above, it will be understood that the pin 2 to which the cam member- 2H] and the gear 2I9 are secured must be rotated one revolution in a counterclockwise direction in order to release the switching unit and return the same to its idle position. In order to insure that the pin 2 is rotated exactly one revolution when the'operating motor M3 is energized, an arrangement is provided which includes a contact set 222 supported by the bracket I99. The contact set 222 includes a pair 01' cooperating flexible contact springs 223 and 224 normally biased into disengagement and adapted to be moved into engagement by the cam member 2| 0, the contact spring 224 being provided with an extended portion adapted to ride upon the periphery of the cam member 2I8. The contact set 222 is included in a secondary energizing circuit for the operating motor M3. In releasing the switch unit, the operating motor M3 is first energized by way of a primary energizing circuit independent of the contact set 222, and after a predetermined rotation of the cam member 2I8, the contact springs of the contact set 222 are engaged. Shortly thereafter, the primary energizing circuit of the operating motor M3 is interrupted, the operating motor being energized only by way of the secondary energizing circuit. 'After the cam member 2) has been rotated one revolution, the projecting end 01 the contact spring 224 rides into a depression 2I8 provided in the periphery of the cam member 2I0, causing the contact springs of the contact set 222 to be disengaged, thereby to interrupt the secondary energizing circuit of the operating motor M3 and to arrest operation thereof.

An arrangement is provided for indicating the idle or particular operated position of the switching unit which comprises three levers 225,226 and 221 pivotally mounted intermediate their ends upon a pin 228 provided on a standard 229 secured by screws 238 to the base plate'28. One end of each of the levers carries a fiag bearing indicia and the other end thereof is pivotally secured to a corresponding one of the racks 9, I28 and I2I. More specifically, one'end of the levers 225, 226 and 221 carries a flag 230, 23I and \232, respectively, and-the other end thereof is secured to the racks H9, I20 and I2I by the pin and slot connections I26, I21 and I28, respectively.' Each of the flags is associated ,with the aperture 33 provided in the escutcheon'plate 34 secured to the fiange 29 extending along the front edge of the switching unit. The indicia provided on each fiag comprises one letter and ten numerals arranged in spaced relation thereon, which are adapted to be moved individually into alignment with the aperture 33 in the estcutcheon plate 34, and which correspond to the normal and the ten ofi-normal positions of the associated operating bar. When the switching unit occupies an idle position, the operating bars 59, 83 and ti occupy their normal positions and the letter N is visible through the aperture 33 in the escutcheon plate 34 on each of the fiangs 230, 23I and 232. On the other hand, when the switching ufiit is operated to any predetermined operating position, the corresponding numerals on the flags 238, 23land 232 are visible through the aperture 33 in the escutcheon plate 34 to indicate the particular operated position of the switching unit.

to engage an extended portion of the contact spring 238. The contact springs of the contact set 233 are moved into disengagement each time the winding I43 of the operating motor MI is energized. The contact set 233 is included in a control circuit more fully described subsequently.

The contact set 280 comprises a pair of cooperating flexible contact springs 28I and 282 biased into engagement and adapted to be moved into disengagement by-an insulating button I19" carried by the arm I19 of the operating motor M2, the button I19 being adapted to engage an extended portion of the contact spring 282. The contact springs of the contact set 280 are moved into disengagement each time the winding I14 of the operating motor M2 is energized. The contact set 280 is also included in a control circuit subsequently described.

A set of contact springs 23! is mounted on a bracket 238 secured by screws'238 to the base plate 28 and associated with' the rack I I9 secured to the hundred bar 59. The contact set 231 comprises a pair of outside contact springs 23S and 240 and an intermediate contact spring 24 I these contact springs being normally in disengagement. The intermediate contact spring 2M carries a roller 242 on the outer end thereof which cooperates with an insulating cam plate 253 secured to the rack i I9. The cam plate 2&5 is provided with an intermediate portion 263 five projections 243 extending outwardly from the intermediate portion and five depressions 243 extending inwardly from the intermediate portion. The intermediate portion 2 i provided on the cam plate 243 corresponds to the normal position of the rack M9; the five projections 2613 provided on the cam plate M3 correspond to the five odd off-normal positions of the rack H9; while the five depressions 243 provided in the cam plate 243 correspond to the five even ofinormal positions of the rack H9. roller 2 32 carried on the outer end of the intermediate spring Zfill engages the intermediate portion 253 of the cam plate 263, the intermediate contact spring 2M disengages the outside contact springs 239 and 240. On the other hand, when the roller 242 engages one of the projections 2 33 on the cam plate 253, the intermediate contact spring 24! is moved into engagement with the outside contact spring 240; and when the roller 2 32 engages one of the depressions 253 provided in the cam plate 243, the intermediate contact spring 2M is moved into engagement with the outside contact spring 239. Thus, when the rack i i 9 occupies its normal position, the contact springs of the contact set 23'! are disengaged; when the rack H9 occupies any odd (iii-normal position, the contact springs 2M and 26% are engaged; and when the rack H9 occupies any even off-normal position, the contact springs 2M and 259cm engaged. The contact set 231 is included in a circuit which is controled in accordance with the odd or even operated position of the rack; i it? and the hundred bar 55 secured thereto, for a purpose subsequently described.

A contact set 245 is associated with the hundred bar 55 and the ten bar 68. The contact set 255 comprises two pairs of contact springs 2 5i, 255 and 25B 252, respectively, the contact springs 2 35 and 252 being provided with extended oprtions 259 and 253 respectively associated with the cam plate 2% carried by therack H9, and a similar cam plate carried by the rack I25, the rack 525 being secured to the ten bar 60. Normally, the

When the 7 contact springs 241', 248 and 25I, 252 are biased into engagement and are moved into disengagement by the cam plates carried by the racks H9 and I 20. These contact springs are so constructed and arranged that when either one of the racks H9 or I is moved intoan off-normal position, both pairs of the contact springs of the contact set 245 are moved into engagement. The contact springs 2", 248 and I, 252 of the contact set 245 are included in a circuit which is controlled in accordance with the normal and ofi-normal positions of the racks H9 and I20 and the hundred bar 59 and the ten bar 60, respectively secured thereto for a subsequently described purpose.

Also, a Jack 254 mounted on a bracket 255, secured to the base plate 28 by the screws 255 is provided, which is disposed in alignment with the opening formed in the fiange 29 extending along the front edge of the switching unit. The jack 254 is adapted to receive a plug inserted through the opening 35 formed in the flange 29, and is wired in a suitable testing circuit in order to provide an arrangement for testing any desired electrical condition of the switching unit.

The escapement control mechanism I54 also constitutes a sequence switch, two contact sets 26!) and 210 being associated therewith. The contact set 250 comprises a pair of cooperating contact springs 26I and 252 biased into engagement, the contact spring 252 being provided with an extended portion 263 adapted to ride upon the periphery of a disc-shaped cam member 264. The cam member 254 is secured to the cam members i151, 1158 and I59, and is rotatable therewith about the pin 856. Four equally spaced-apart depressions 255 are provided in the periphery of the cam member 255 which correspond to the fourth off-normal positions of the ratchet wheel I55. When the ratchet wheel I55 of the escapement control mechanism I55 occupies its fourth offnormal position, the extended portion 265 provided on the contact spring 262 rides into one of the depressions 256 in the periphery of the cam member 255, causing the contact springs 2M and 262 of the contact set 250 to be moved into engagement. The contact set 265 is included in a circuit which is controlled by the movement of the escapement control mechanism I54 into its fourth off-normal position. The contact set 210 comprises a pair of cooperating contact springs 2H and M2 biased into disengagement, the contact spring 2112 being provided with an extended portion 2'53 adapted to ride upon the periphery of a disc-shaped cam member 274. The cam member 2'84 is secured to the cam members I51, i525 and i155 and is rotatable therewith about the pin 255. Four equally spaced-apart depressions 255 are provided in the periphery of the cam member 256 which correspond to the normal or fifth ofi-norxnal positions of the ratchet wheel i55. When the ratchet wheel H55 of the escapemerit control mechanism I54 occupies its normal or fifth oft-normal position, the extended portion 2'33 provided on the contact spring 212 rides into one of the depressions 215 in the periphery of the cam member 215, causing the contact springs 2' and 25E of the contact set 270 to be moved into disengagement. The contact set 210 is included in a circuit which is controlled by the movement 

